1. Field of the Invention
The present invention relates to a bearing apparatus of sealing type including roll neck bearings used, for example, in iron and steel facilities or rolling machines.
2. Description of the Related Art
As roll neck bearings to be used to work rolls of hot rolling machines, cold rolling machines or intermediate rolls, it is conventional to use tapered roller bearings in double-row or four-row capable of supporting large load.
In such rolling machines, much cooling water is supplied to the work rolls for precisely securing thickness of products and controlling shapes thereof. Accordingly, a sealing device is inherently required to the roll neck bearing for avoiding invasion of the cooling water into the interior of the bearing.
The sealing device equipped with a seal of contacting type as described in JP-A-6-82437U is, in general, broadly used, but has a problem of causing heat at a sliding face of the seal. In particular since a high speed operation of rolling machines has recently been designed for background of increasing productivity, relatively large clearances or gaps in an interior of the bearings have been made, taking thermal expansion into consideration. However, an eccentric amount in the seal of the contacting type of the sealing device is therefor increased, resulting to lower the sealing ability or increase heat in the seal sliding face so that the contacting seal is worn or damaged at an earlier period. Further, though heat resistance of the contacting seal may be considered to improve it, a new problem arises that cost will be heightened.
On the other hand, there is a sealing device provided with a seal of non-contacting type such as labyrinth seal as described in JP-B-3-66963. Being without the sliding part, the sealing device of such type has no problem of heating the seal and may comply with the rolling machine operated at high speed, but when operated at relatively low speed, the labyrinth effect, which makes use of a centrifugal force, is compromised.
In a case of the non-contacting seal as the labyrinth seal, for inspecting the interior of the bearing and supply grease, the labyrinth seals are generally fixed at inner and outer races on the circumference with may bolts, to thereby assemble and disassemble them. This case, however, increases the number of parts, is complicated in a structure of the sealing device, and assembling and disassembling procedures are inefficient.
Accordingly, in view of such problems as mentioned, it is an object of the invention to provide a compact bearing apparatus of sealing type enabling to comply with machines to be driven a high speed, while heightening the sealing ability at low speeds.
In view of such problems as mentioned, it is another object of the invention to provide a bearing apparatus of sealing type enabling to heighten the sealing ability though at low cost and having excellent assembling and disassembling ability.
To solve the above object, there is provided a bearing apparatus of sealing type, comprising: tapered rollers disposed in four rows and a sealing body comprising an elastic material, which contacts a sliding face of a seal when the bearing apparatus rotates at low speed and does not contact the sliding face or reduces a contacting pressure by deformation due to a centrifugal force when the bearing apparatus rotates at high speed.
The bearing apparatus of sealing type according to the invention is incorporated with the tapered rollers disposed in four rows and the sealing body comprising an elastic material which contacts a sliding face of the sealing body at low speed, and does not contact the sliding face or reduces a contacting pressure by deformation due to a centrifugal force acting on itself at high speed. Therefore, for example, the elastic material contacts the sliding face at low speed so as to form a contacting seal, thereby to compensate a low speed-low sealing ability of the non-contacting seal such as the labyrinth seal, and on the other hand, at high speed, the elastic material lowers the contacting pressure by deformation due to the centrifugal force, otherwise the non-contacting seal as the labyrinth seal is formed by the non-contacting condition, whereby it is possible to solve the problem of heating or abrasion at the contacting part.
In addition to the above seal, a combination with the non-contacting seal is preferable. The seal and the non-contacting seal may be one or plural.
In addition, the bearing apparatus of the invention comprises an inner race having a holding face, an outer race, a rolling member rotatably arranged between the inner and outer races, a sealing body for sealing a space between the inner and outer races, and a holding member detachably holding the sealing body. Accordingly, the holding member is fitted into the holding face of the inner race, to thereby secure the equipment of the sealing device, without processing a screwing hole for equipping the sealing device to the inner race. As the holding member can be optionally processed with the screwing hole, the sealing device may be secured thereto by means of, e.g., screws.
It is preferable that the sealing body is devised to fit into, e.g., the holder, so that a handling property is excellent.
Moreover, the bearing apparatus according to the invention comprises an inner race, an outer race, rolling members rotatably arranged between the inner and outer races, and the sealing device for sealing a space between the inner and outer races. The sealing device comprises an outer race member and an inner race member encircled by the outer race member, and a sealing unit disposed between the inner and outer race members. The sealing unit comprises a projection part furnished to the inner race member and formed continuously in the circumferential direction and a sealing face part furnished to the outer race member and extending in the circumferential direction. The projection part contacts the sealing face part, when the inner race member rotates at a speed lower than the predetermined speed, but when the inner race member rotates at a speed more than the predetermined speed, the projection part reduces the contacting pressure to the sealing face part or separates from the sealing face part so as to form a non-contacting seal in relation with the sealing face part. Thus, for example, the projection part contacts the sealing face part to form the contacting seal at low speed, thereby to compensate the low speed-low sealing ability of the non-contacting seal such as the labyrinth seal, and on the other hand, at high speed, the projection part lowers the contacting pressure to the sealing face part, otherwise the non-contacting seal as the labyrinth seal is formed by separating therefrom, whereby it is possible to solve the problem of heating or abrasion at the contacting part. If the projection part is positioned at a side of the interior space of the bearing with respect to the sealing face part, the projection part does not disturb approach and separation of the sealing face part when assembling or disassembling, and therefore the bearing apparatus having the excellent assembling and disassembling abilities may be offered.
Herein, the term of xe2x80x9cnon-contacting sealxe2x80x9d is defined by a seal having such function as the labyrinth seal that foreigners as a water adhered to the projection part are thrown to a side of the sealing face part by a shaking-off effect making use of the centrifugal force to thereby exhaust them outside. The outer race member may be integrally formed with the outer race or separated therefrom, and the inner race member may be integrally formed with the inner race or separated therefrom.
Further, it is preferable that the outer race member is provided with a drain passage, whereby a draining effect is heightened.
Still further, it is preferable that the outer race member is defined with a circumferential groove in the edge of the bearing of outer race member, to thereby prevent a water from entering the interior of the bearing from the edge of the bearing.
Moreover, it is preferable that the sealing part of the sealing device is formed in a cylindrical shape.